The versatile forward is set for a spell on the sidelines after dislocating his shoulder on Friday night.
Ryan suffered the injury in the 12th minute of Munster's Magners League win over Edinburgh at Musgrave Park.
The 26-year-old is awaiting further medical tests to discover the extent of the injury but he will almost certainly miss the Magners League clash with the Dragons at Rodney Parade on March 6.
The injury also brings an end to Ryan's spell in the Ireland squad for Saturday's Six Nations encounter with England at Twickenham.
Ryan made his senior international bow against Italy at the beginning of the month but it is feared he will now have to wait until the summer tour before making another Irish appearance.
Munster also have injury concerns over full back cum fly-half Paul Warwick and flanker Niall Ronan following the 19-12 win over Edinburgh.
Warwick's dead leg is expected to have cleared before the trip to Newport but Ronan faces an anxious wait for further medical analysis before his involvement in the next installment of Magners League action can be confirmed.
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